Encyclopedia of Islands

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Islands Surrounded by the Sea

Come island-hopping with me. . . . On Tenerife, in the Canary Islands, I´m standing at a roadside and gazing at a shoreline far below, where Atlantic surf breaks on lava boulders. In an apricot tree immediately before me, three small gray birds with yellowish breasts alight and start singing. They are - what else? - –°anaries.  But don´t be misled. The islands were named not for the birds but for large native dogs once found here: Canis became Canaria became Canary, and the birds inherited the name. Oddities like this are part of the fun of islands, part of the individuality that can make even a small island a world in its own right.

Over the years, I´ve been lucky enough to visit quite a few islands. I´ve explored the Hawaiian group. I´ve exchanged moody stares with the stone statues of Easter Island, remnants of the sort of puzzling island culture that can develop when generations pass without contact from overseas. I´ve been dripped on in the rain forests of the Queen Charlotte Islands off the west coast of Canada, where aged, moss-covered totems still brood. I´ve trod the crusty lava flows of Iceland, where even the sunsets seem cold and distant, and I´ve dozed against coconut palms in Tahiti, where the sun seems to set in your lap and the clouds threaten to burst into flame. I´ve sweltered in the scurry and bustle of Hong Kong, island of commerce. And I´ve heard the clang of a cell door slamming shut on the prison island of Alcatraz: Isolation is no guarantee of paradise.

Canary Islands

An island, geographers say, is any area of land surrounded by water. Then what about Australia? No. It´s so big it´s considered an island continent. Greenland at 840,000 square miles ranks as the world´s largest island, while islets shade off into rocks at the other end of the scale.

Some experts sort the world´s uncountable islands into two broad categories: oceanic and continental. Oceanic islands are usually born of volcanic eruption, far from major landmasses. Such is Bouvet, uninhabited and alone in the South Atlantic: perhaps the most isolated of all, with no land for a thousand miles in any direction. Continental islands have become separated from—naturally—continents, and therefore can boast of an ancient and varied geologic history. Their island identity, however, may begin with the recent Ice Age: As the ice sheets melted, the sea level rose and flooded low-lying coasts, marooning such high ground as the British Isles, Sri Lanka, Newfoundland, and Manhattan.

In fact, islands originate in many ways. Often their formation stems from the workings of plate tectonics: the ponderous movement of tremendous plates of rock in the earth´s crust, floating upon a denser, hotter subterranean layer. It´s their pulling apart and pushing together that reshape landmasses. Forces generated by this titanic movement break off majestic islands like Madagascar from continental rims and uplift others, like Japan, along the edges of the plates.

When an oceanic plate moves over a "hot spot" in the underlying layer, molten rock may build up one volcanic island after another in a linear chain—the Hawaiian group and the Galápagos are good examples. Other volcanic islands, such as Iceland, form along great rifts in the ocean floor where plates are pulling apart and releasing molten rock from far below.